A simpler PTAS for connected <Emphasis Type="Italic">k</Emphasis>-path vertex cover in homogeneous wireless sensor network

Because of its application in the field of security in wireless sensor networks, k-path vertex cover (\(\hbox {VCP}_k\)) has received a lot of attention in recent years. Given a graph \(G=(V,E)\), a vertex set \(C\subseteq V\) is a k-path vertex cover (\(\hbox {VCP}_k\)) of G if every path on k vertices has at least one vertex in C, and C is a connected k-path vertex cover of G (\(\hbox {CVCP}_k\)) if furthermore the subgraph of G induced by C is connected. A homogeneous wireless sensor network can be modeled as a unit disk graph. This paper presents a new PTAS for \(\hbox {MinCVCP}_k\) on unit disk graphs. Compared with previous PTAS given by Liu et al., our method not only simplifies the algorithm and reduces the time-complexity, but also simplifies the analysis by a large amount.     

An $$O(|E(G)|^2)$$ algorithm for recognizing Pfaffian graphs of a type of bipartite graphs

A graph \(G=(V,E)\) with even number vertices is called Pfaffian if it has a Pfaffian orientation, namely it admits an orientation such that the number of edges of any M-alternating cycle which have the same direction as the traversal direction is odd for some perfect matching M of the graph G. In this paper, we obtain a necessary and sufficient condition of Pfaffian graphs in a type of bipartite graphs. Then, we design an \(O(|E(G)|^2)\) algorithm for recognizing Pfaffian graphs in this class and constructs a Pfaffian orientation if the graph is Pfaffian. The results improve and generalize some known results.     

Competition and Coordination in Two‐Tier Public Service Systems under Government Fiscal Policy

As a result of government budgetary limits and rapid market growth, many public service systems—such as health care—are characterized by extensive customer wait times that have become a serious problem. This problem might be solved by allowing private firms to enter these markets, which would provide customers with a choice between a free (governmental) public service provider (SP) and a fee‐charging (or “toll”) private SP. In such a two‐tier service system, the two SPs are differentiated by service quality and cost efficiency. This study focuses on the competition and coordination issues for two‐tier service systems with customers who are sensitive to both service quality and delay. The free system attempts to maximize its expected total customer utility with limited capacity, whereas the toll system attempts to maximize its profit. Neither goal is aligned with the social welfare goal of the public service. To achieve the social welfare goal, the government plays a crucial role in coordinating the two‐tier service system via the budget, the tradeoff of social members' goals, and tax‐subsidy policies. Using a mixed duopoly game, we establish Nash equilibrium strategies and identify the conditions for the existence of the two‐tier service system. We employ several interesting and counter‐intuitive managerial insights generated by the model to show that the public service can be delivered more efficiently via customer choice and SP competition. In addition, we show that a relatively low tax‐subsidy rate can almost perfectly coordinate the two SPs to achieve most of the maximum possible benefit of the two‐tier service system.     

现金持有在企业投资支出中的平滑作用——基于融资约束的视角

由于内外部融资具有不确定性,可能导致企业投资支出发生波动。而投资支出的变化会引发高昂的调整成本,因此企业有必要保持投资支出的相对稳定。本文重点关注企业在保持投资支出稳定的过程中,现金持有在平滑投资中的作用。以沪深两市A股上市公司1998-2010年的面板数据为样本,利用带凸性调整成本的动态投资模型,首先检验了现金持有对投资支出在总体样本中的平滑作用。然后进一步引入融资约束的视角,通过分组回归,比较分析了在不同融资约束程度下现金持有对投资的平滑作用的差异。研究表明,现金持有对企业投资有显著平滑作用,且这种平滑作用在融资约束程度较高的企业中表现得更为明显。本文的研究丰富了现有文献,为我国上市公司现金持有政策和投资决策的制定提供了一定的理论和实证依据。     

家族企业文化调节作用下的家族成员影响活动与企业绩效

家族企业是典型的企业家控制型企业,企业家的决策质量直接影响企业绩效,因此家族企业主集权的负面效应一直是家族企业可持续性发展的障碍。文章以与委托代理活动共存于企业中的另一种交易活动——影响活动作为切入点,研究发现在家族企业中影响活动并不像现有研究认为的那样只存在负面影响,反而是显著提高了企业绩效,而组织文化在其中发挥了关键的调节作用。影响活动正面效应的发现对于决策机制尚未正式化的家族企业很有意义,研究结论对影响成本理论的发展和家族企业研究都具拓展性作用,同时也是一次本土化研究的有益尝试。     

联盟网络联系、公平感知与联盟绩效的关系——基于中国科技创业联盟的实证研究

通过对中国3个城市的科技创业联盟204家创业企业的问卷调查,对联盟网络规模、关系强度、公平感知与联盟绩效之间的关系进行了实证分析,并采用Johnson-Neyman法对公平感知的调节效应进行了量化分析。结果表明,在中等或以上公平感知水平,联盟网络规模对联盟绩效具有显著正向影响;而在低公平感知水平,联盟网络规模对联盟绩效的影响不显著。联盟关系强度对联盟绩效有显著正向影响,并且,随着成员公平感知水平的提高,关系强度对联盟绩效的促进作用越强。可见,建设公平的创业环境,对于加强科技创业联盟合作,促进科技创业发展有着重要的意义。     

产品造型对用户使用意向影响的事件相关电位研究

产品设计能否激发用户的使用意向将决定用户产生进一步体验行为或制定购买决策,传统方法难以保证对用户自身感觉的准确解析。大脑控制着人的一切行为和认知,神经生理学的发展及其测量方法的成熟使从脑认知的角度研究用户体验成为可能。采用事件相关电位技术,以智能手机为研究对象,探索期望体验的形成过程。为尽可能保证脑认知差异是由产品造型激发的期望体验不同而引起的,实验不考虑产品价格和品牌的影响。实验中要求被试浏览不同用户体验水平的智能手机造型,等概率随机呈现这些智能手机造型,当出现能诱发被试使用意向的手机时,要求被试点击鼠标左键。以点击鼠标行为数据(有/无产生期望体验意向)作为脑电处理的依据,将采集的脑信号经过Curry 7.0 SBA处理,然后通过SPSS 18.0对各个时间窗内的事件相关电位的平均幅值进行被试内重复测量方差分析。研究结果表明,在被试对于呈现的智能手机造型产生期望体验意向并做出点击鼠标行为时,与无期望体验意向时相比,能在额区-中央区诱发较小的峰潜伏期的260毫秒左右的负波(N2)和峰潜伏期在400毫秒左右的正波(P3),在中-顶区、顶区和枕区引起更大的峰潜伏期在300毫秒左右的负波(N3)和晚期正波(LPP);头皮地形图显示当被试产生期望体验意向时,被试中-顶区、顶区和枕区得到更强激活。脑电信号可以反映用户有无期望体验意向,也能间接反映产品设计的好坏。通过对用户脑信号的分析,能够提供更精确的测量用户感知的方法,帮助市场研究者更好地锁定用户的心理需求。     

整合能力与企业绩效：商业模式创新的中介作用

经济全球化的背景下,企业为了构建竞争优势,获取更好的绩效,开始利用整合能力和商业模式创新应对多变的外部环境。然而,当前研究对于两者之间存在何种联系的认识是模糊的。针对理论研究的缺陷,基于动态能力的理论视角,通过分析商业模式创新对整合能力与企业绩效的中介作用,揭示企业整合能力和商业模式创新促进企业绩效提高的内在机制,采用中国6省1市319个企业样本数据,运用线性回归的统计方法对理论假设进行实证检验。研究结果表明,整合能力和商业模式创新都对企业绩效具有正向的促进作用,同时整合能力与企业绩效之间存在着一定的中间机制。整合能力通过提高组织变革和价值创造效率两个方面促进商业模式创新,而商业模式创新作为中间纽带将整合能力与企业绩效联系起来。企业的整合能力越高,越有利于开展商业模式创新,进而促进企业绩效的提高。研究揭示了整合能力和商业模式创新共同促进企业绩效提高的内在理论机制,打开了能力与绩效间关系的“黑箱”,对于中国企业开展商业模式创新具有重要的实践指导意义。